Adjustable spring counterbalance for power drills



Sept. 8, 1931. L. F. MEUNIER ADJUSTABLE SPRING COUNTERBALANCE FOR POWER DRILLS Filed Feb. 15, 1928 2 Sheets-Sheet l R m w W 190/7 5 Mean/,

ATTORNEY.

P 8, 1931- L. F. MEUNIER 1,822,231

ADJUSTABLE SPRING COUNTERBALANCE FOR POWER DRILLS Filed Feb. 15. 1928 2 Sheets-Sheet 2 INVENTOR. lea/7 E Meun/r A TTORNE Y.

Patented Sept. 8, 1931 UNITED STATES PATENT OFFICE LEON F. MEUNIER, OF CLEVELAND, OHIO, ASSIGNOR TO CHICAGO PNE'UMATIO TOOL COMPANY, OF NEW YORK, 11'. Y., A CORPORATION OF NEW JERSEY CJI ADJUSTABLE SPRING OOUNTERBALANOE FOR POWER DRILLS Application filed February 15, 1928.

This invention relates to supports particularly adapted and intended for use with power operated tools. More specifically it concerns tool supporting frames arranged to be manually controlled and directed.

Among the objects of the invention are to provide a device of the described type having both manual and automatic control means, to arrange the automatic means so as to urge the supported tool toward and yieldingly to maintain it at one limit of its movement, to provide for adjustment of the automatic means to the weight of the tool which is to be supported or to the WOIK which is to be performed, and in general to improve prior devices in the interest of more efficient and satisfactory service.

This invention comprises a support and a frame adapted for limited movement upon the support and to which the power tool is secured. The automatic means for control ling the position of the frame relative to the support may be of any suitable or desired type. r A spring motor is particularly suitable by reason of the yielding character of the force exerted by it. Such a motor may be arranged to urge the frame and the tool carried thereby either toward the work in theform of an automatic feed or away from the work when the tool is intended for direct manual control of its operation.

In order to illustrate the invention one concrete embodiment thereof is shown in the accompanying drawings in which:

Figs. 1 and 2 are respectively front and side elevational views of the support with a power tool indicated in broken outline as supported thereon:

Fig. 3 is a sectional view substantially on the line 3-3 of Fig. 1, the power tool as well as certain portions of the movable frame being omitted; and

Fig. is a sectional view substantially on the line 44 of Fig. 3.

In the drawings the machine or power tool to be supported is indicated'at'li, the movable frame to which the tool is secured at B and the support for the movable frame at C. The power tool A may be of any suitable or desired type and may be secured to frame B Serial No. 25%,399.

in any desired manner. The machine indicated is electrically operated and intended for driving securing members such as bolts, studs, nuts, screws, and the like.

l Vhile supportC may be of a fixed character, if desired, it is shown in the present instance secured to a sliding arm D (Figs. 2 and 3) which arm may be arranged for both horizontal and vertical adjustment upon a suitable member, such as a pedestal.

In the form chosen for the purpose of illustration moveable frame B comprises spaced side members of slides 5 connected together at their opposite ends by transverse members 6 upon which may be provided suitable clamping means at 7 for securing power tools or machines, such as A, to the frame. The side members 5 are slidable in guide sleeves 8 on a yoke 9 (Fig. 3) forming a part of support C. Sleeves 8 cooperate with transverse members 6 to form stops defining the limits of the movement of frame B relative to support C.

' In order to control the movement of frame B the side members 5 of the same are provided with rack teeth 10 within sleeves 8, which rack teeth are engaged by pinions 11 keyed to a shaft 12 supported for rotation in bearings 13 on support C (Fig. 3) The left side of support C, as viewed in Figs. 1 and 3, is formed with an enlarged casing 14 which not only encloses the pinion 11 on the proximate end of shaft 12 but also houses a drum 15 keyed to the same end of the shaft. A'

cover 16 is arranged to be secured over the open end of casing 14 as by screw bolts 17.

l/Vithin casing 14 is disposed the automatic means forcontrolling the position of frame B relative to support C. Such means preferably take the form of a spring motor comprising a volu'te spring 18 of heavy spring material having its outer end suitably secured to the inner periphery of drum 15 as by a headed bolt 19 extending through an aperture in the spring and provided with a cotter pin 20 (Fig. 4) The inner end of spring 18' is secured to a fixed support, such as a projection 21 on cover 16 as by a bolt 22. As indicated in Fig. 3, projection 21 extends within drum 15 in axial alignment with shaft 12 and may have a socket or recess 22 receiving boss or projection 23 on the end of shaft 12. lVhile spring 18 of the motor may be arranged to act upon drum 15 through shaft 12 and the rack and pinion connection 10-11, so as to move frame B in either direction; in the present instance, it tends to move frame B toward and yieldingly to maintain the latter at the upper limit of its movement.

To accommodate the supporting apparatus to power tools of differing weights as well as to adapt the same for feeding a tool to the work with any desired degree of force if the motor is arranged to drive the frame toward the work, provision is made for adjusting the tension of spring 18. To this end projection 21 takes the form of a stub shaft having a bearing 24 in cover 16 and a bearing at 22 on boss 25 Stub shaft 21 also has a radial flange 21a engaging the outer face of cover 16 and arranged to be fixedly secured thereto in any position of angular adjustment by one or more screws 25. Shaft 21 also has a polygonally shaped. end 26 for the application for a wrench for turning the shaft when spring 18 is to be tightened or loosened. To assist in adjustin shaft 21 and to hold it temporarily in adjusted position while fastening screws 25 are inserted or removed, flange 21a is cut away at suitable points to provide teeth arranged to be engaged by a dog or pawl 27 on cover 16.

In order to operate frame B either with or I against the spring motor, the end of shaft 12 remote from the motor extends beyond a cover 28 for the pinion chamber and has socured to its projecting end a handle 29. It is thus apparent that manual control handle or lever 29 actuates frame B through the same shaft and rack and pinion driving connection as the automatic control means. In the particular form of the invention shown in the drawings lever 29 is utilized to move frame B downwardly in opposition to the spring motor to bring power tool A in contact with the work and to feed it to the work. Upon release of pressure of the operator on handle 29 the spring motor immediately operates to move frame B upwardly and to withdraw tool A from contact with the work.

Support C may have a fixed handle 30 secured thereto in any convenient position, as at the base of guide sleeve 8 and adjacent casing 14 of the spring motor. Handle 30 will be grasped by the left hand of the operator while his right hand operates control lever 29. If the tool which is supported in frame B is electrically operated as shown. the main switch therefor may be disposed upon support C adjacent the spring motor and convenient to the left hand of the operator, as indicated at 81 in Fig. 2.

It is to: be understood that the above disclosure is for illustrative purpose only and that the invention is intended to coversuch changes, modifications and adaptations as fall within the scope of the appended claims.

I claim as my invention:

1. A support for a power tool having a movable frame to which the tool is secured, said frame having spaced slide members, guide sleeves on said support slidably receiving said members and limiting the movement of said frame, rack teeth on said members, a shaft on said support having pinions meshing with the teeth on said members, a drum on said shaft, a casing on said support enclosing said drum, a cover for said casing, a volute spring within said drum having its outer end secured to the latter, and a shaft on said cover projecting within said drum to which the inner end of said spring is secured, said last named shaft being adjustable to vary the torque exerted by said spring upon said pinion shaft, said shafts being axially aligned and having parts in telescoped interengagement to maintain their alignment while permitting independent relative rotation of said shafts.

A support for a power tool having a movable frame to which the tool is secured, said frame having spaced slide members, guide sleeves on said support slidably receiving said members and limiting the movement of said frame, rack teeth on said members, a shaft on said support having pinions meshing with the teeth on said members, a drum on said shaft, a casing on said support enclosing said drum, a cover for said casing, a voiute spring within said drum having its outer end secured to the latter, a stub shaft in line with said pinion shaft and having hearings in said cover and upon the end of said pinion shaft, the inner end of said spring being secured to said stub shaft, and means for adjustably securing said stub shaft to said cover against angular movement thereby to provide for varying the torque exerted by said spring in accordance with the weight of the tool which is mounted upon said frame.

Si ned by me at Clevelanchin the County of Cuyahoga and State of Ohio this 28 day of January, 1928.

LEON F. MEUNIER. 

